91 olds toronado cluster dead

on a 91 olds toronado it has a cluster that only the tach works, when plugged in the hvac control show a dotted line without functionality. when the cluster is unplugged the bcm comes back to life with working chime and hvac. I checked all the powers and grounds and non at fault, the way the wake up is depicted makes me want more description of operation. back probing the cluster was not really possible, unplugged got battery voltage on the wake up. did find faults in the cluster, top pic third blue resister to the right burnt solder points and on what could be a cap with a tan rap that im unsure about. on the second there is what looks like two diodes and the left one looks to have overheated, all fets and ic's look to be in good shape. I had the owner find out about a replacement cluster, if got a understanding what caused this malfunction repairing this cluster may be a option.

It looks like the BCM is responsible for sending the wake up voltage to the cluster. The BCM likely gets power from the key switch.

You can probably reflow the solder on the resistors and if you can get specs on the cap and diode replace them. It's hard to say if the cluster will come back after repairs or not but hell is try it!

Check to see if the wake up line is hot all the time or if it's switch like it should be. If it's hot all the time start looking at the BCM.

Companies like Moser and digikey should have those board components for a few nickels.

yes the bcm gives the on trigger and off its ground, what puzzles me is why they would use a voltage divider over a regulator. what I can think of off that is there probably is on/reset for a ic and/or they are using the bleed off to drain the caps for faster suit down. another test I did that was not mentioned is I probed that pin to see what i had when on and it would trip the bcm. so is this a blown cap or diode that made this circuit too low resistance to ground, or am I barking up the wrong tree that this issue is from the bcm's trigger. I am going to attack what is know first and that is the ipc. the alien cap that went with the blue resistor would need reflow as well, on its top was 100uf (I believe I was thinking of something else pic somewhat shows 102k) but what type cap is that because ive never seen one like that. what Im thinking is a diode is another variable because there is like 10 differnt types so yes knowledge of this circuit would be key. there is another issues with this car that may or may not be related, the blower be on low when off and the owner unplugs it so it does not drain the battery. when the bcm is tripped it will not shut down and functionality of interior lights is unknown. found a youtube vid that shows similar situation but is intermittent, what is mentioned as the issues is a cps but am not finding anything on it in alldata. I do see a tsb for codes b333-337 with a flow chart, may want to see if it will flash out any bcm codes. I am going to do more digging about this central power supply module and this ipc. oh and this one has the analog cluster



www.justanswer.com/oldsmobile/4h2me-olds...toronado-trofeo.html

I had the owner send the cluster out the other day to get repaired since the only option at the time, I left it out so the car could be driven with bcm function working. puzzles dont sit well unsolved so continued digging, what I figured out so far is that tan raped object is a choke inductor. to why a noise isolator is used is unknown but could be due to the transformer, but the issue is why there was a overdraw of current through this choke and a diode. I am not going to pull the repaired cluster apart and further test are going to before I install the cluster. I am going to go through the wiring diagrams to come up with a full damage control plan of action to ensure this damage was not caused by the car for when I go back out to the car. not sure if this relevant but the cluster died when the person was driving on the highway

the cluster got repaired and found nothing else out of place, I capered a waveform of c4 and d4. put the cluster in and it did not come on but it did not trip the bcm for about 10 seconds. this does not make too much sense since I have powers and ground on both cluster and bcm. I am going to think this out and go back out monday to do further test.

owner got back in town and went to check this out again earlier, I am back to another dead end. The BCM has all good powers and grounds, there is a good 5v ref but the 5v return that is dead. The IPC wake up goes from 12v to 10v with the cluster plugged in. For that 5v return there is no listing of it on any of the diagrams except for the connector read out, so am unsure about it. Pulled the BCM apart and found no issues with it, so not enough to call a BCM. So do I still got a bad cluster, BCM or some other mysteries entanglement. I wonder if I can talk to this over the aldl,. I am waiting on a adapter cable to use these OEM connectors I got that was missing from the kit.